please help in interfacing at24c256 and parallel port

Discussion in 'Embedded Systems and Microcontrollers' started by efm, Nov 14, 2006.

  1. efm

    Thread Starter Member

    Sep 14, 2006
    14
    0
    hello,

    i'm trying to write and read my at24c256 eeprom through parallel port. i have schematics from
    atmel (interfacing at24c32 and 8051), from www.phanderson.com/printer/24c32 (interfacing at24c32
    and parallel port), and from mcmcc.bat.ru/serp (at24cxx and parallel port), but none of them is
    working.

    please could someone let me know how to wire the at24c256 and parallel port, with simple
    program (just for reading and writing a byte), or at least point me to a website that covers this thing.

    btw, i'm using SuSE 10.

    please help,

    faizal
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    Given the amount of material presented at the web site, things should work. Have you compared the spec sheet on the 256 device with the example 24C23 serial eprom? There could be significant differences.

    Can you post up a schematic of your circuit? Also, you may be running Suse10, but on what hardware platform? How is the parallel port configured?
     
  3. efm

    Thread Starter Member

    Sep 14, 2006
    14
    0
    hello,
    thanks for the reply,

    hmm...there is some differences between at24c32 and at24c256...
    on at24c32, the pins 1, 2, and 3, are labeled A0, A1, A2 (address pin), while on the
    at24c256, they're labeled A0, A1, and NC...will this be a problem? because in every schematics
    those pins are grounded,

    here is the features of at24c32:
    Code ( (Unknown Language)):
    1. Features
    2. • Low-Voltage and Standard-Voltage Operation
    3.     – 2.7 (VCC = 2.7V to 5.5V)
    4.     – 1.8 (VCC = 1.8V to 5.5V)
    5. • Low-Power Devices (ISB = 2 µA at 5.5V) Available
    6. • Internally Organized 4096 x 8, 8192 x 8
    7. • 2-Wire Serial Interface
    8. • Schmitt Trigger, Filtered Inputs for Noise Suppression
    9. • Bidirectional Data Transfer Protocol
    10. • 100 kHz (1.8V, 2.5V, 2.7V) and 400 kHz (5V) Clock Rate
    11. • Write Protect Pin for Hardware Data Protection
    12. • 32-Byte Page Write Mode (Partial Page Writes Allowed)
    13. • Self-Timed Write Cycle (10 ms max)
    14. • High Reliability
    15.     – Endurance: 1 Million Write Cycles
    16.     – Data Retention: 100 Years
    17. • Automotive Grade and Extended Temperature Devices Available
    18. • 8-Pin JEDEC PDIP, 8-Pin JEDEC SOIC, 8-Pin EIAJ SOIC,
    19.   and 8-pin TSSOP Packages
    and the features of at24c256:
    Code ( (Unknown Language)):
    1. Features
    2. • Low Voltage and Standard Voltage Operation
    3.     – 5.0 (VCC = 4.5V to 5.5V)
    4.     – 2.7 (VCC = 2.7V to 5.5V)
    5.     – 1.8 (VCC = 1.8V to 3.6V)
    6. • Internally Organized 16,384 x 8 and 32,768 x 8
    7. • 2-Wire Serial Interface
    8. • Schmitt Trigger, Filtered Inputs for Noise Suppression
    9. • Bidirectional Data Transfer Protocol
    10. • 1 MHz (5V), 400 kHz (2.7V) and 100 kHz (1.8V) Compatibility
    11. • Write Protect Pin for Hardware and Software Data Protection
    12. • 64-Byte Page Write Mode (Partial Page Writes Allowed)
    13. • Self-Timed Write Cycle (5 ms typical)
    14. • High Reliability
    15.     – Endurance: 100,000 Write Cycles
    16.     – Data Retention: 40 Years
    17.     – ESD Protection: > 4000V
    18. • Automotive Grade and Extended Temperature Devices Available
    19. • 8-Pin JEDEC PDIP, 8-Pin JEDEC and EIAJ SOIC, 14-Pin TSSOP, and
    20.   8-Pin Leadless Array Packages
    the first schematic, scheme.jpg, i got from http://mcmcc.bat.ru/serp,
    and the second, myscheme.jpg is my design, i just delete the 93xxx because i don't use it

    thank you
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    What is the purpose of the address pins? In the serial programmer schematic, they are shown floating - neither tied high or low.

    Assuming the address pins may be ignored, what are the protocols for setting up the serial eprom for reading out data, or for writing data in? I'm sure you'll have to tell the chip what to do before it will work. Also - did you notice that the write cycle on the 256 device is twice as fast as the 32? That could affect something.
     
  5. efm

    Thread Starter Member

    Sep 14, 2006
    14
    0
    hello beenthere,

    the a0, a1, and a2 is for chip selection i guess. if you wire seven more of that chip together, then the
    selection of which chip to store the data is through those pins. the datasheet says that they're low by
    default if they're not tied.

    hmm..i didn't notice the write cycle before...that could be a problem...
    i just bought another 24c256 and some 24c32s, in case that mine is broken,
    i'll try them tonight...

    thank you,

    faizal
     
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